Single-phase earth fault line selection method, device and equipment and storage medium

Abstract

The invention discloses a single-phase earth fault line selection method, device and equipment and a storage medium, and relates to the field of power system fault detection, and the method comprises the steps: obtaining a fault detection result through employing a bus zero-sequence voltage break variable at a current moment determined based on a baseline voltage reference value at the current moment; the fault detection result comprises a fault occurrence moment and a fault transient state time period; performing transient component extraction on the bus zero-sequence voltage data and the outgoing line zero-sequence current data corresponding to the fault transient time period; determining virtual compensation current data of the outgoing line based on the extracted bus zero-sequence voltage transient component and the ground capacitance of the outgoing line; determining a compensated transient energy ratio of the outgoing line based on the virtual compensation current data and the extracted zero-sequence current transient component of the outgoing line; and determining the transient characteristic difference degree of each outgoing line based on the compensated transient energy ratio, and comparing the difference degrees to screen out a target fault outgoing line. According to the invention, the problem of low accuracy and reliability in the traditional scheme can be solved.

Description

Technical Field

[0001] This invention relates to the field of power system fault detection, and in particular to a method, apparatus, equipment and storage medium for selecting a single-phase grounding fault. Background Technology

[0002] In power systems, single-phase grounding faults are a common and highly dangerous type of fault. However, current single-phase grounding fault location schemes have many shortcomings. For example, traditional schemes rely on the amplitude and phase of zero-sequence current for fault location. In systems grounded through arc suppression coils, the difference in zero-sequence current characteristics between the faulty and non-faulty lines is weakened due to the compensation effect of the arc suppression coils, leading to a decrease in the accuracy of fault location. In addition, traditional schemes based on steady-state quantities are easily affected by the initial phase angle of the fault, transition resistance, and changes in system operating conditions, making it difficult to accurately identify the faulty line under complex operating conditions. In other words, traditional single-phase grounding fault location schemes have low accuracy and reliability. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a method, apparatus, device, and storage medium for single-phase ground fault location, which can solve the problems of low accuracy and reliability in traditional solutions, effectively improve the accuracy and reliability of single-phase ground fault location, and increase the efficiency of single-phase ground fault location. The specific solution is as follows:

[0004] Firstly, this application provides a method for locating single-phase ground faults, applied in power systems, including:

[0005] The bus zero-sequence voltage mutation is determined based on the baseline voltage reference value at the current moment, and a single-phase ground fault is detected based on the bus zero-sequence voltage mutation to obtain the fault detection result; the fault detection result includes the fault occurrence time and the fault transient time period corresponding to the fault occurrence time.

[0006] Based on a preset high-pass filter, transient components are extracted from the bus zero-sequence voltage data and outgoing zero-sequence current data corresponding to the fault transient time period in the fault detection results, so as to determine the transient component extraction results.

[0007] Based on the preset virtual compensation current model and the ground capacitance of each outgoing line, as well as the bus zero-sequence voltage transient component in the transient component extraction result, the virtual compensation current data corresponding to each outgoing line is determined; the preset virtual compensation current model includes a preset capacitive reactance compensation coefficient.

[0008] Based on the virtual compensation current data and the transient component of the zero-sequence current of the outgoing line in the transient component extraction result, the compensation transient energy ratio of each outgoing line is determined.

[0009] Based on the compensated transient energy ratio of each of the outgoing lines, the transient characteristic difference degree of each of the outgoing lines is determined, and single-phase grounding fault line selection is performed by comparing the magnitude of the transient characteristic difference degree to determine the selected target fault outgoing line.

[0010] Optionally, determining the bus zero-sequence voltage mutation based on the baseline voltage reference value at the current moment, and performing single-phase ground fault detection based on the bus zero-sequence voltage mutation, includes:

[0011] By monitoring the zero-sequence voltage of the bus and combining it with the median filtering of the historical time offset within the sliding time window, the baseline voltage reference value at the current time can be determined.

[0012] Based on the baseline voltage reference value at the current moment and the monitored bus zero-sequence voltage at the current moment, determine the bus zero-sequence voltage change at the current moment;

[0013] Determine whether the zero-sequence voltage change of the bus is greater than a preset voltage change threshold to determine the change judgment result; wherein, the preset voltage change threshold is a preset proportion of the rated phase voltage;

[0014] If the result of the mutation amount determination is yes, then the current time is recorded as the time when the fault occurred;

[0015] If the result of the mutation amount judgment is negative, it is determined that no single-phase ground fault has occurred in the line, and the process jumps back to the step of determining the baseline voltage reference value at the current moment by monitoring the zero-sequence voltage of the bus and performing median filtering in combination with the historical time offset within the sliding time window.

[0016] Based on the time of the fault occurrence and the number of sampling points, the sampling interval and the transient time length of the coverage fault are determined;

[0017] Based on the time of the fault occurrence and the length of the transient time, the fault transient time period is determined;

[0018] Based on the number of sampling points and the sampling interval, the zero-sequence voltage of the bus and the zero-sequence current of each outgoing line are collected at each moment during the fault transient time period to determine the zero-sequence voltage data of the bus and the zero-sequence current data of the outgoing lines.

[0019] Optionally, the step of extracting transient components from the bus zero-sequence voltage data and outgoing line zero-sequence current data corresponding to the fault transient time period in the fault detection results based on a preset high-pass filter includes:

[0020] Obtain the preset Butterworth high-pass filter;

[0021] Based on the transfer function corresponding to the preset Butterworth high-pass filter, the bus zero-sequence voltage data and the outgoing line zero-sequence current data at each moment in the fault transient time period are subjected to high-pass filtering to determine the transient component extraction result.

[0022] Optionally, determining the virtual compensation current data corresponding to each outgoing line based on a preset virtual compensation current model, the ground capacitance of each outgoing line, and the bus zero-sequence voltage transient component in the transient component extraction results includes:

[0023] Obtain the capacitance to ground for each outgoing line;

[0024] Obtain a preset virtual compensation current model; wherein, the preset virtual compensation current model is a model constructed based on the principle of electromagnetic induction, the principle of capacitor charging and discharging, the rate of change of the transient component of the zero-sequence voltage of the bus, and a preset capacitive reactance compensation coefficient; the preset capacitive reactance compensation coefficient is a capacitive reactance compensation coefficient determined based on the ground capacitance of the power system;

[0025] The ground capacitance and the bus zero-sequence voltage transient component from the transient component extraction result are input into the preset virtual compensation current model to determine the virtual compensation current data corresponding to each outgoing line.

[0026] Optionally, obtaining the capacitance to ground of each outgoing line includes:

[0027] By injecting a harmonic current of a preset frequency into the secondary side of the bus voltage transformer, the voltage at the harmonic current injection point and the current of each outgoing line are collected.

[0028] Based on a bandpass filter, harmonic extraction is performed on the voltage at the harmonic current injection point and the current of each of the outgoing lines to determine the voltage harmonic components and the current harmonic components corresponding to each of the outgoing lines.

[0029] Based on the voltage harmonic components and the current harmonic components corresponding to each of the outgoing lines, the capacitance to ground of each outgoing line is determined.

[0030] Optionally, determining the compensated transient energy ratio of each outgoing line based on the virtual compensation current data and the outgoing line zero-sequence current transient component in the transient component extraction result includes:

[0031] Based on the transient component of the zero-sequence current in the extracted transient component, the original transient current energy of each of the outgoing lines is determined.

[0032] The energy of the compensated transient current of each outgoing line is determined by subtracting the transient component of the zero-sequence current of the outgoing line from the corresponding virtual compensation current data.

[0033] Based on the original transient current energy and the compensated transient current energy, the compensated transient energy ratio of each of the outgoing lines is determined.

[0034] Optionally, determining the transient characteristic difference degree of each of the outgoing lines based on the compensated transient energy ratio of each outgoing line, and selecting the single-phase ground fault line by comparing the magnitude of the transient characteristic difference degree, includes:

[0035] For any of the aforementioned outgoing lines, the compensated transient energy ratio of the current outgoing line is compared with the average of the compensated transient energy ratios of the other outgoing lines excluding the current outgoing line, in order to determine the degree of difference in transient characteristics of the current outgoing line;

[0036] The transient feature differences are sorted to determine the sorting result.

[0037] Based on the sorting results, single-phase grounding fault line selection is performed to determine the selected target fault line.

[0038] Secondly, this application provides a single-phase ground fault location device, applied in a power system, comprising:

[0039] The fault detection module is used to determine the bus zero-sequence voltage mutation amount at the current moment based on the baseline voltage reference value at the current moment, and to perform single-phase grounding fault detection based on the bus zero-sequence voltage mutation amount to obtain the fault detection result; the fault detection result includes the fault occurrence time and the fault transient time period corresponding to the fault occurrence time.

[0040] The transient component extraction module is used to extract transient components from the bus zero-sequence voltage data and outgoing zero-sequence current data corresponding to the transient time period of the fault detection result based on a preset high-pass filter, so as to determine the transient component extraction result.

[0041] The virtual compensation current determination module is used to determine the virtual compensation current data corresponding to each outgoing line based on a preset virtual compensation current model, the ground capacitance of each outgoing line, and the bus zero-sequence voltage transient component in the transient component extraction result; the preset virtual compensation current model includes a preset capacitive reactance compensation coefficient.

[0042] The transient energy ratio determination module is used to determine the compensated transient energy ratio of each of the outgoing lines based on the virtual compensation current data and the transient component of the zero-sequence current in the transient component extraction result.

[0043] The fault selection module is used to determine the transient characteristic difference degree of each of the outgoing lines based on the compensated transient energy ratio of each outgoing line, and to select the single-phase grounding fault line by comparing the magnitude of the transient characteristic difference degree, so as to determine the selected target fault outgoing line.

[0044] Thirdly, this application provides an electronic device, comprising:

[0045] Memory, used to store computer programs;

[0046] A processor is used to execute the computer program to implement the steps of the aforementioned single-phase ground fault location method.

[0047] Fourthly, this application provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of the aforementioned single-phase ground fault location method.

[0048] As can be seen, in this application, applied to a power system, the bus zero-sequence voltage mutation is determined based on the baseline voltage reference value at the current moment, and single-phase grounding fault detection is performed based on the bus zero-sequence voltage mutation to obtain the fault detection result; the fault detection result includes the fault occurrence time and the fault transient time period corresponding to the fault occurrence time; based on a preset high-pass filter, transient components are extracted from the bus zero-sequence voltage data and outgoing zero-sequence current data corresponding to the fault transient time period in the fault detection result to determine the transient component extraction result; based on a preset virtual compensation current model... The virtual compensation current data corresponding to each outgoing line is determined based on the ground capacitance of each outgoing line and the bus zero-sequence voltage transient component in the transient component extraction results. The preset virtual compensation current model includes a preset capacitive reactance compensation coefficient. Based on the virtual compensation current data and the outgoing line zero-sequence current transient component in the transient component extraction results, the compensated transient energy ratio of each outgoing line is determined. Based on the compensated transient energy ratio of each outgoing line, the transient characteristic difference degree of each outgoing line is determined, and single-phase grounding fault line selection is performed by comparing the magnitude of the transient characteristic difference degree to determine the selected target fault outgoing line. In other words, this application first determines the bus zero-sequence voltage mutation based on the baseline voltage reference value at the current moment in the power system. Single-phase grounding faults are detected based on this mutation to determine the fault detection result. Then, the bus zero-sequence voltage data and outgoing line zero-sequence current data in the fault detection result are high-pass filtered to obtain transient component extraction results. Next, based on a preset virtual compensation current model, the ground capacitance of each outgoing line, and the bus zero-sequence voltage transient component in the transient component extraction results, the corresponding virtual compensation current data for each outgoing line is determined. Then, based on the virtual compensation current data and the outgoing line zero-sequence current transient component in the transient component extraction results, the compensated transient energy ratio of the outgoing line is determined. Based on the compensated transient energy ratio, the transient characteristic difference degree of each outgoing line is determined. The target fault outgoing line is selected based on the magnitude of the difference degree. In this way, this application can solve the problems of low accuracy and reliability in traditional schemes, effectively improving the accuracy and reliability of single-phase grounding fault location and increasing the efficiency of single-phase grounding fault location. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0050] Figure 1 A flowchart of a single-phase grounding fault location method provided in this application;

[0051] Figure 2 A flowchart of a specific single-phase grounding fault location method provided in this application;

[0052] Figure 3 A schematic diagram of a single-phase grounding fault selection device provided in this application;

[0053] Figure 4 This application provides a structural diagram of an electronic device. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Current single-phase grounding fault location schemes have many shortcomings. For example, traditional schemes rely on the amplitude and phase of zero-sequence current for fault location. However, in grounding systems with arc suppression coils, the difference in zero-sequence current characteristics between the faulty and non-faulty lines is weakened due to the compensation effect of the arc suppression coils, leading to a decrease in the accuracy of fault location. In addition, traditional schemes based on steady-state quantities are easily affected by changes in the initial phase angle of the fault, transition resistance, and system operating mode, making it difficult to accurately identify the faulty line under complex operating conditions. In other words, traditional single-phase grounding fault location schemes have low accuracy and reliability.

[0056] Therefore, this application provides a single-phase grounding fault location scheme, which can solve the problems of low accuracy and reliability in traditional schemes, effectively improve the accuracy and reliability of single-phase grounding fault location, and improve the efficiency of single-phase grounding fault location.

[0057] See Figure 1 As shown, this embodiment of the invention discloses a method for selecting a single-phase grounding fault, applied to a power system, including:

[0058] Step S11: Determine the bus zero-sequence voltage mutation amount at the current time based on the baseline voltage reference value at the current time, and perform single-phase grounding fault detection based on the bus zero-sequence voltage mutation amount to obtain the fault detection result; the fault detection result includes the fault occurrence time and the fault transient time period corresponding to the fault occurrence time.

[0059] Combination Figure 2As shown, in this embodiment, the bus zero-sequence voltage is first monitored in real time, and the bus zero-sequence voltage mutation is calculated. When the mutation exceeds the rated phase voltage at a set ratio, the fault occurrence time is obtained. The transient time length and sampling frequency covering the fault are set to collect the bus zero-sequence voltage and the zero-sequence current of each outgoing line at each moment. That is, by monitoring the bus zero-sequence voltage and combining it with the median filtering of the historical time offset within the sliding time window, the baseline voltage reference value at the current moment is determined. Based on the baseline voltage reference value at the current moment and the monitored bus zero-sequence voltage at the current moment, the bus zero-sequence voltage mutation at the current moment is determined. It is then determined whether the bus zero-sequence voltage mutation exceeds a preset voltage mutation threshold to determine the mutation judgment result. Wherein, the preset voltage mutation threshold is a preset threshold. The proportional rated phase voltage; if the change in magnitude judgment result is yes, then the current time is recorded as the fault occurrence time; if the change in magnitude judgment result is no, then it is determined that no single-phase ground fault has occurred in the line, and the process jumps back to the step of determining the baseline voltage reference value at the current time by monitoring the zero-sequence voltage of the bus and performing median filtering based on the historical time offset within the sliding time window; based on the fault occurrence time and the number of sampling points, the sampling interval and the transient time length covering the fault are determined; based on the fault occurrence time and the transient time length, the fault transient time period is determined; based on the number of sampling points and the sampling interval, the zero-sequence voltage of the bus and the zero-sequence current of each outgoing line at each moment in the fault transient time period are collected to determine the bus zero-sequence voltage data and the outgoing line zero-sequence current data.

[0060] This enables high-precision dynamic monitoring of bus zero-sequence voltage surges, allowing for rapid location of fault occurrences and improved fault identification sensitivity. It also preserves transient characteristics, providing a reliable data foundation for subsequent line selection based on transient characteristics.

[0061] Regarding the specific procedures for detecting the above-mentioned faults:

[0062] (1) Real-time monitoring of the zero-sequence voltage of the bus, and construction of a dynamic baseline reference value through sliding time window and median filtering, to calculate the abrupt change in the zero-sequence voltage of the bus, i.e.:

[0063] ;

[0064] In the formula, This represents a dynamic baseline voltage reference value; To represent median filtering, in order to suppress transient interference (such as lightning strikes, switching operations, etc.); This indicates the offset of a historical moment within the time window; Indicates the first The zero-sequence voltage of the bus at that moment; Indicates the duration of the sliding window; Indicates the first The sudden change in the zero-sequence voltage of the bus at any given moment; Indicates the first The zero-sequence voltage of the bus at time t.

[0065] In this embodiment, the design principle of this step is as follows: when the distribution network is operating normally, the bus zero-sequence voltage Approaching 0 (three-phase balance); after a single-phase ground fault occurs, the voltage of the faulty phase decreases, while the voltage of the non-faulty phases increases, leading to a sudden increase in zero-sequence voltage (e.g., Therefore, by constructing a dynamic baseline reference value and combining it with the real-time monitored bus zero-sequence voltage, the sudden change in bus zero-sequence voltage can be calculated, thereby determining whether the distribution network is operating normally. Thus, this embodiment, by combining the dynamic baseline with the calculation of the sudden change, can clearly distinguish between normal fluctuations and fault sudden changes, thereby accurately capturing fault sudden changes and improving fault identification sensitivity. Among them, the bus zero-sequence voltage is measured by installing a voltage transformer (PT, Potential Transformer) on the bus.

[0066] Furthermore, this embodiment also introduces a sliding time window and median filtering to construct a dynamic baseline reference value, which satisfies dynamic adaptability and anti-interference, conforms to the "normal state" of the current system, and utilizes abrupt changes. Quantifying voltage jumps caused by faults allows for accurate identification of even minute fault signals. Simultaneously, dynamic baseline correction addresses the issue of traditional fixed baselines failing to adapt to normal system fluctuations (such as seasonal variations in capacitor current and load switching), thus reducing the abrupt changes in the zero-sequence bus voltage. It can reflect the true fault, thereby improving the sensitivity of fault identification; at the same time, the median filter used is more effective than the mean filter in suppressing transient interference (lightning strikes, switching operations), which conforms to signal processing principles, can reduce the false trigger rate, and enhance anti-interference capability; among them, the dynamic baseline voltage reference value calculation formula is: ;and The value is taken as 1 minute before the fault occurs, with the purpose of covering the normal fluctuation cycle of the system.

[0067] (2) Determine whether the sudden change in the zero-sequence voltage of the busbar is greater than the rated phase voltage under the set ratio. If so, a fault occurs, and the time of fault occurrence is recorded. Then, proceed to the next step; otherwise, if the line is normal, continue with step (1). The rated phase voltage under the set ratio is:

[0068] ;

[0069] In the formula, This indicates the rated phase voltage. In this embodiment, it is set to 15%. By quantifying fault criteria, accurate triggering and reliable differentiation can be achieved in power system fault identification, specifically in the following ways:

[0070] 1) Suppressing normal system fluctuations: During normal operation of the distribution network, due to three-phase load imbalance, voltage transformer errors, etc., there are inherent fluctuations in the zero-sequence voltage (usually <10%). ); and setting it at 15% As a threshold, these normal fluctuations can be effectively filtered out, avoiding misjudgments and thus accurately locating the fault boundary.

[0071] 2) Achieve precise capture of fault sudden changes: During a single-phase ground fault, the zero-sequence voltage sudden change is typically >10%. (e.g., high-resistance grounding 5%-15%); 15% The threshold can cover more than 90% of high-resistance grounding faults (fault resistance ≤ 5000Ω), thereby improving the high-resistance fault identification rate.

[0072] (3) When a fault is detected, based on the time of the fault occurrence, the sampling interval and the transient time length of the fault coverage are set, then the number of sampling points is:

[0073] ;

[0074] In the formula, The sampling interval is represented by T; the transient time of the coverage fault is represented by N; and the total number of sampling points is 100.

[0075] In this embodiment, to ensure complete coverage of the duration of the high-frequency transient components after the fault occurs (the transient process of a single-phase ground fault in a distribution network is typically 1-10 ms, while 5 ms is the "characteristic enrichment region" of a typical fault), T is set to 5 ms (i.e., covering the typical fault time). Simultaneously, to satisfy the Nyquist sampling theorem and prevent aliasing of the transient signal, thereby reducing sampling error, The value is 50μs; therefore, the final total number of sampling points is . =5ms / 50μs=100.

[0076] (4) Based on the sampling interval and the number of sampling points, collect the zero-sequence voltage of the bus and the zero-sequence current of each outgoing line at each time point, i.e.:

[0077] ;

[0078] In the formula, K represents the total number of qualifying lines; Let represent the zero-sequence current of outgoing line k at time t; represents the zero-sequence voltage of the bus at time t; n represents the sampling point.

[0079] Step S12: Based on a preset high-pass filter, extract transient components from the bus zero-sequence voltage data and outgoing line zero-sequence current data corresponding to the fault transient time period in the fault detection results, so as to determine the transient component extraction results.

[0080] In this embodiment, the transient components of the sampled data in the fault detection results are extracted, that is, a preset Butterworth high-pass filter is obtained; based on the transfer function corresponding to the preset Butterworth high-pass filter, the bus zero-sequence voltage data and the outgoing line zero-sequence current data at each moment in the fault transient time period are high-pass filtered to determine the transient component extraction result. The preset Butterworth high-pass filter can be a fourth-order Butterworth high-pass filter; that is, a fourth-order Butterworth high-pass filter is selected, and the bus zero-sequence voltage and the zero-sequence current of each outgoing line at each moment are high-pass filtered to obtain the transient components of the bus zero-sequence voltage and the zero-sequence current of each outgoing line at each moment.

[0081] It should be understood that the purpose of selecting a 4th-order Butterworth high-pass filter to extract each transient component in this embodiment is:

[0082] (1) Obtaining smooth passband ripples: The amplitude response of the Butterworth filter is the flattest in the passband. The fourth-order Butterworth high-pass filter allows the high-frequency signals that need to be retained in the transient components (transient signals usually contain rich high-frequency components) to pass through with a relatively uniform gain, minimizing the amplitude distortion of the signal in the passband, and ensuring that the original characteristics of the transient voltage and current components are not excessively changed, so that the results are more reliable when analyzing faults based on these components.

[0083] (2) Effective stopband attenuation: For low-frequency components that are not needed in the power system (such as power frequency components and below steady-state and slow-varying interference), the fourth-order Butterworth high-pass filter can provide sufficient attenuation in the stopband, which can better suppress these low-frequency interferences, highlight transient components, and make the extracted transient signal "pure", which is convenient for accurate analysis of fault transient characteristics.

[0084] Specifically, the transfer function of the fourth-order Butterworth high-pass filter is:

[0085] ;

[0086] In the formula, H represents the transfer function; s represents the complex frequency variable in the Laplace transform; This represents the gain coefficient, which takes a value of 1. The complex frequency is represented by the real part, and j represents the imaginary unit. q represents the imaginary part of the complex frequency, i.e., the angular frequency; q represents the order. Indicates the actual pole; The cutoff frequency is 500Hz; sin and cos represent the sine and cosine functions, respectively.

[0087] Specifically, the transient components of the zero-sequence voltage of the bus and the transient components of the zero-sequence current of each outgoing line at each time point are as follows:

[0088] ;

[0089] In the formula, HPF represents a 4th-order Butterworth high-pass filter; This represents the transient component of the zero-sequence current of line k at time t. This represents the transient component of the zero-sequence voltage of the bus at time t.

[0090] Step S13: Based on the preset virtual compensation current model and the ground capacitance of each outgoing line, and the bus zero-sequence voltage transient component in the transient component extraction result, determine the virtual compensation current data corresponding to each outgoing line; the preset virtual compensation current model includes a preset capacitive reactance compensation coefficient.

[0091] In this embodiment, after extracting the transient components, a capacitive reactance compensation coefficient is introduced. By compensating for the ground capacitance of each outgoing line and the transient components of the bus zero-sequence voltage at each time point, a virtual compensation current model is constructed to obtain the virtual compensation current. That is, the ground capacitance of each outgoing line is obtained; a preset virtual compensation current model is obtained; wherein, the preset virtual compensation current model is a model constructed based on the principles of electromagnetic induction, capacitor charging and discharging, the rate of change of the bus zero-sequence voltage transient component, and the preset capacitive reactance compensation coefficient; the preset capacitive reactance compensation coefficient is a capacitive reactance compensation coefficient determined based on the ground capacitance of the power system; the ground capacitance and the bus zero-sequence voltage transient component from the transient component extraction results are input into the preset virtual compensation current model to determine the virtual compensation current data corresponding to each outgoing line.

[0092] It is understood that in this embodiment, in the distribution network, the capacitance to ground of each outgoing line is... A charging and discharging current will be generated when the transient component of the zero-sequence voltage of the bus changes; according to the relationship between capacitor current and voltage change rate ( , For capacitor current, For capacitors, (for voltage), utilizing the ground capacitance of each outgoing line. The rate of change of the transient component of the zero-sequence voltage of the bus ( This allows the construction of a virtual compensation current; where a capacitive reactance compensation coefficient is introduced. This is to adapt to the actual operation of the distribution network, where differences between the system impedance, distributed parameters, and other factors and the ideal model exist. It corrects the theoretically calculated capacitive current (counteracting the capacitive current) to make the virtual compensation current more closely resemble actual fault characteristics. Therefore, based on the principles of electromagnetic induction and capacitor charging and discharging, the capacitance to ground of each outgoing line is... Differential of the transient component of the zero-sequence voltage of the bus Correlation, multiplied by the capacitive reactance compensation coefficient It can simulate the theoretical compensation current generated by the capacitance to ground of non-faulty lines during a fault, providing a key basis for subsequent energy analysis and difference calculation for fault line selection.

[0093] Specifically, the preset virtual compensation current model is as follows:

[0094] ;

[0095] In the formula, This represents the virtual compensation current of outgoing line k at time t; This represents the capacitive reactance compensation coefficient, which is dimensionless and has a value of 1.2. It represents the derivative of the transient component of the zero-sequence voltage of the bus at each moment, which reflects the rate of change of the electric field.

[0096] Furthermore, in this embodiment, the capacitive reactance compensation coefficient... It can be adjusted according to the total ground capacitance of the distribution network system, and can adapt to distribution networks of different scales (such as different numbers of outgoing lines and line lengths) and different operating states (such as changes in ground capacitance due to seasonal variations). Under complex operating conditions such as high-resistance grounding and distributed power source access, the compensation effect can be optimized by adjusting α to ensure the robustness of the line selection method, thereby improving the line selection accuracy under complex operating conditions and solving the problem of misjudgment and omission by traditional methods in complex scenarios.

[0097] In one specific implementation, The value can be obtained through simulation experiments. Specifically, using professional power system simulation software (such as PSCAD / EMTDC (Power Systems Computer Aided Design, an electromagnetic transient simulation software, whose core is the electromagnetic transient simulation program), various typical distribution network models are built, including scenarios with different numbers of outgoing lines (e.g., 5, 10, 15 outgoing lines), different line lengths (short lines, medium-long lines, long lines), different operating states (changes in ground capacitance in different seasons such as summer and winter), and various complex operating conditions (high-resistance ground fault resistance ranging from 100Ω to 5000Ω, different access capacities and locations of distributed power sources, etc.). Then, a large number of simulation experiments are conducted on each scenario to try different... The values ​​were varied (e.g., from 0.8 to 1.5, tested in steps of 0.1), and the accuracy of fault location was statistically analyzed for different values. Finally, through analysis and comparison of the simulation results, it was found that when... When the value is 1.2, the fault location accuracy reaches a high level in most simulation scenarios, and compared with other values, the fluctuation of the location accuracy is smaller and the stability is better. Therefore, from the perspective of simulation testing, this embodiment selects 1.2 as a relatively optimal default value.

[0098] It is important to understand that, regarding the acquisition of ground capacitance, this embodiment installs a voltage transformer on the secondary side of the busbar and employs an online harmonic input method. By injecting a harmonic current of a specific frequency into the secondary side of the busbar voltage transformer, the ground capacitance of each outgoing line is acquired. Specifically: by injecting a harmonic current of a preset frequency into the secondary side of the busbar voltage transformer, the voltage at the harmonic current injection point and the current of each outgoing line are collected; based on a bandpass filter, harmonic extraction is performed on the voltage at the harmonic current injection point and the current of each outgoing line to determine the voltage harmonic components and the corresponding current harmonic components for each outgoing line; based on the voltage harmonic components and the corresponding current harmonic components for each outgoing line, the ground capacitance of each outgoing line is determined. This avoids the power outage losses caused by the traditional offline voltage application method, and allows for periodic or automatic measurement activation after a fault, enabling dynamic updates of the capacitance value for subsequent steps to calculate the virtual compensation current. Specifically:

[0099] (1) Inject a harmonic current of a specific frequency into the secondary side of the bus voltage transformer, and collect the voltage at the injection point and the current of each outgoing line, i.e.:

[0100] ;

[0101] In the formula, This represents the harmonic current of a specific frequency injected into the secondary side of the bus voltage transformer at time t. This represents the effective value of the harmonic current, which is set according to the actual situation, generally 1A, 2A, etc.; sin represents the sine value. Indicates a specific frequency; This represents the current in line k at time t; Let t represent the voltage at the injection point at time t.

[0102] In this embodiment, the specific frequency, i.e., the frequency of the injected harmonic current, needs to be selected to avoid the power frequency (50Hz) and its harmonic interference in order to reduce errors. For example, a value of 225Hz is used. Therefore, the injected harmonic current is a sinusoidal current corresponding to the specific frequency. That is, the specific frequency determines the frequency characteristics of the harmonic current, and the harmonic current is a sinusoidal current signal at that specific frequency.

[0103] (2) A bandpass filter is used to extract harmonics from the injection point voltage and each outgoing line current to obtain the voltage harmonic components and the current harmonic components, i.e.:

[0104] ;

[0105] In the formula, Represents voltage harmonic components; It represents the harmonic components of the current; BPF stands for bandpass filter.

[0106] In this embodiment, the bandpass filter (BPF) thoroughly filters out power frequency (50Hz) and other interfering harmonics by extracting only the harmonics of the injected specific frequency (such as 225Hz), thereby improving the purity of voltage and current harmonic components and providing accurate "noise-free" input for subsequent capacitance calculations. This avoids capacitance calculation errors caused by interfering harmonics and suppresses system noise interference.

[0107] (3) Based on the voltage harmonic components and current harmonic components, calculate the capacitance to ground of each outgoing line, i.e.:

[0108] ;

[0109] In the formula, This represents the capacitance to ground of line k, in units of... In this embodiment, To convert a unit farad (F) to a microfarad (µF) Furthermore, the formula: The advantages of this design are: molecules For the pure harmonic component of capacitive current, in the denominator For the same frequency and constant voltage, The frequency parameter is used to naturally cancel out the influence of system impedance and obtain a more accurate capacitance to ground. That is, the influence of system impedance (such as line resistance and inductance) will affect both voltage and current, and will naturally cancel out in the ratio calculation.

[0110] Step S14: Based on the virtual compensation current data and the transient component of the zero-sequence current of the outgoing line in the transient component extraction result, determine the compensated transient energy ratio of each outgoing line.

[0111] In this embodiment, after obtaining the virtual compensation current data, the energy ratio is analyzed by combining the transient component of the zero-sequence current of the outgoing line in the transient component extraction result. That is, based on the transient component of the zero-sequence current of the outgoing line in the transient component extraction result, the original transient current energy of each outgoing line is determined; by subtracting the transient component of the zero-sequence current of the outgoing line from the corresponding virtual compensation current data, the compensated transient current energy of each outgoing line is determined; based on the original transient current energy and the compensated transient current energy, the compensated transient energy ratio of each outgoing line is determined.

[0112] Specifically, the formula for calculating the transient energy ratio after compensation for each outgoing line is as follows:

[0113] ;

[0114] In the formula, This represents the transient energy ratio after compensation for line 𝑘.

[0115] It should be understood that in this embodiment, when a single-phase ground fault occurs in the distribution network, the zero-sequence current of each outgoing line includes two parts: (1) Non-faulted outgoing lines: only include the ground capacitance current (the ground capacitance naturally exists during normal system operation, and the capacitance current will increase significantly during a fault, but it is essentially an "interference quantity" and does not reflect the fault location); (2) Faulted outgoing lines: in addition to the ground capacitance current, they also include the transient current injected by the fault source (which is an effective signal that truly reflects the fault location); therefore, the above-mentioned virtual compensation current The objective is to counteract the interference of capacitive current; therefore, this formula... In the middle, the compensation items With ground capacitance Transient component of zero-sequence voltage of bus Dynamic correlation accurately matches the transient characteristics of capacitive current; therefore, the transient component of zero-sequence current is included. Subtract compensation items This can filter out the interference of the ground capacitance current, allowing the remaining part to... It more closely resembles the characteristics of fault source injection, highlighting the difference between faulty outgoing lines and non-faulty outgoing lines.

[0116] In summary, molecules The denominator represents the transient current energy after compensation. This represents the original transient current energy. For a healthy line (i.e., a non-faulty outgoing line), the compensation term is... It will cancel out the original current The non-faulty components in the molecules, thus making the molecules ≈0, meaning the transient energy ratio after compensation for line k is 0. The value approaches 0; however, for faulty outgoing lines, the compensation item... The fault component cannot be offset, resulting in a significant residual current. This leads to a numerator that is much greater than 0, causing the transient energy ratio after line k compensation to be lower than that of the fault component. The value is significantly greater than that of a healthy line (usually close to or exceeding 1). Therefore, the faulty outgoing line can be identified based on the calculated transient energy ratio after compensation for each outgoing line.

[0117] Step S15: Based on the compensated transient energy ratio of each outgoing line, determine the transient characteristic difference degree of each outgoing line, and select the single-phase grounding fault line by comparing the magnitude of the transient characteristic difference degree, so as to determine the selected target fault outgoing line.

[0118] In this embodiment, after obtaining the transient energy ratio after compensation for each outgoing line, it is necessary to calculate the transient characteristic difference degree of each outgoing line to determine the outgoing line that has experienced a fault. By sorting the transient characteristic difference degrees of each outgoing line from smallest to largest, the outgoing line corresponding to the largest transient characteristic difference degree is obtained, which is the selected faulty outgoing line. That is: for any outgoing line, the compensated transient energy ratio of the current outgoing line is compared with the average of the compensated transient energy ratios of the other outgoing lines to determine the transient characteristic difference degree of the current outgoing line; the outgoing lines are sorted based on the magnitude of the transient characteristic difference degree to determine the sorting result; and single-phase grounding fault line selection is performed based on the sorting result to determine the selected target faulty outgoing line.

[0119] Specifically, the formula for calculating the transient characteristic difference of each line is:

[0120] ;

[0121] In the formula, This represents the degree of transient characteristic difference of line k; This represents the transient energy ratio after compensation for line j.

[0122] It should be understood that in this embodiment, the transient characteristic difference degree of each outgoing line is calculated. The purpose is:

[0123] (1) Solve the problem of "energy ratio similarity" and strengthen the differentiation of fault characteristics; for example, the ground capacitance of multiple outgoing lines may be similar (such as cables of the same type and length), and the energy ratio after compensation The differences are small, and during the fault transient process, electromagnetic interference may cause abnormal fluctuations in the energy ratio of some non-faulty outgoing lines, which can be confused with the energy ratio of faulty outgoing lines; therefore, the transient characteristic difference is small. The design, through the calculation logic of "energy ratio of a single outgoing line / average energy ratio of the remaining outgoing lines", can amplify the energy ratio difference between faulty and non-faulty outgoing lines (faulty outgoing lines). It will be significantly greater than the non-faulty outgoing lines), while suppressing the local similarity among non-faulty outgoing lines (even if the energy ratios of multiple non-faulty outgoing lines are similar, their mean can still be lowered). This finally solved the problem of "misjudging similar lines" that might occur if only the energy ratio is used, making the characteristics of faulty lines more prominent.

[0124] (2) Adapt to complex topologies with multiple outgoing lines and improve robustness; Due to the complexity of distribution network topologies (such as radial, ring networks, and multiple outgoing lines), during a fault: the fault current distribution of different outgoing lines is greatly affected by the topology and load, and simply comparing the absolute value of the energy ratio cannot adapt to all scenarios; and under extreme conditions (such as the fault point being close to the busbar or weak feeder), the energy ratio of the faulty outgoing line may be less different from that of the non-faulty outgoing line; therefore, the transient characteristic difference of each outgoing line should be calculated. Regardless of topology changes, faulty lines will... It is always the ratio of its own energy ratio to the average of the other outgoing lines, and can adapt to the energy distribution of different topologies; and in weak feed scenarios, even if the absolute value of the energy ratio of the faulty outgoing line is small, as long as it differs greatly from the average of other outgoing lines, It can still effectively identify [the virus], and its decision-making logic is simple and easy to implement.

[0125] In this way, by combining relative difference calculation with sorting and filtering, the limitations of comparing absolute values ​​of energy ratios are solved, adapting to complex topologies and extreme working conditions, simplifying engineering decision-making logic, and serving as a key link from "data characteristics" to "fault line", thus making the fault line selection method more intelligent and practical.

[0126] In summary, the single-phase grounding fault location scheme proposed in this embodiment has the following beneficial effects:

[0127] (1) A single-phase grounding fault line selection scheme based on transient compensation characteristics is proposed. By constructing a dynamic baseline reference value and combining it with the real-time monitored bus zero-sequence voltage, the sudden change of the bus zero-sequence voltage is obtained, realizing high-precision dynamic monitoring and enabling rapid fault detection and determination of the fault occurrence time.

[0128] (2) By constructing a virtual compensation current model, the virtual compensation current is obtained to offset the interference of capacitive current, which can accurately match the transient characteristics of capacitive current. At the same time, the virtual compensation current is used to compensate the transient component of zero-sequence current. By filtering out the interference of capacitive current, the transient component of residual current is closer to the characteristics of fault source injection, thereby highlighting the difference between faulty outgoing lines and non-faulty outgoing lines, and improving the accuracy and reliability of fault line selection.

[0129] (3) Using the difference in transient characteristics after compensation as the criterion for line selection, compared with the existing scheme that uses the original signal as the criterion, this embodiment can amplify the energy ratio difference between the faulty line and the non-faulty line, thereby strengthening the distinction of fault characteristics and significantly improving the accuracy of fault line selection.

[0130] Therefore, in this application, the bus zero-sequence voltage mutation is first determined based on the baseline voltage reference value at the current moment in the power system. Single-phase grounding faults are detected based on this mutation to determine the fault detection result. Then, the bus zero-sequence voltage data and outgoing line zero-sequence current data in the fault detection result are high-pass filtered to obtain transient component extraction results. Next, based on a preset virtual compensation current model, the ground capacitance of each outgoing line, and the bus zero-sequence voltage transient component in the transient component extraction results, the corresponding virtual compensation current data for each outgoing line is determined. Then, based on the virtual compensation current data and the outgoing line zero-sequence current transient component in the transient component extraction results, the compensated transient energy ratio of the outgoing line is determined. Based on the compensated transient energy ratio, the transient characteristic difference degree of each outgoing line is determined. The target fault outgoing line is selected based on the magnitude of the difference degree. In this way, this application can solve the problems of low accuracy and reliability in traditional schemes, effectively improving the accuracy and reliability of single-phase grounding fault location and increasing the efficiency of single-phase grounding fault location.

[0131] See Figure 3 As shown in the figure, this application also discloses a single-phase ground fault location device, applied in a power system, comprising:

[0132] The fault detection module 11 is used to determine the bus zero-sequence voltage mutation amount at the current time based on the baseline voltage reference value at the current time, and to perform single-phase grounding fault detection based on the bus zero-sequence voltage mutation amount to obtain the fault detection result; the fault detection result includes the fault occurrence time and the fault transient time period corresponding to the fault occurrence time.

[0133] The transient component extraction module 12 is used to extract transient components from the bus zero-sequence voltage data and outgoing zero-sequence current data corresponding to the fault transient time period in the fault detection result based on a preset high-pass filter, so as to determine the transient component extraction result.

[0134] The virtual compensation current determination module 13 is used to determine the virtual compensation current data corresponding to each outgoing line based on a preset virtual compensation current model, the ground capacitance of each outgoing line, and the bus zero-sequence voltage transient component in the transient component extraction result; the preset virtual compensation current model includes a preset capacitive reactance compensation coefficient.

[0135] The transient energy ratio determination module 14 is used to determine the compensated transient energy ratio of each of the outgoing lines based on the virtual compensation current data and the transient component of the zero-sequence current in the transient component extraction result.

[0136] The fault selection module 15 is used to determine the transient characteristic difference degree of each of the outgoing lines based on the compensated transient energy ratio of each outgoing line, and to select the single-phase grounding fault line by comparing the magnitude of the transient characteristic difference degree, so as to determine the selected target fault outgoing line.

[0137] In some specific embodiments, the fault detection module 11 may specifically include:

[0138] The baseline voltage reference value determination unit is used to determine the baseline voltage reference value at the current moment by monitoring the zero-sequence voltage of the bus and combining it with the median filtering of the historical time offset within the sliding time window.

[0139] The voltage mutation determination unit is used to determine the bus zero-sequence voltage mutation at the current moment based on the baseline voltage reference value at the current moment and the bus zero-sequence voltage monitored at the current moment.

[0140] A sudden change determination unit is used to determine whether the sudden change in the zero-sequence voltage of the bus is greater than a preset voltage sudden change threshold, so as to determine the sudden change determination result; wherein, the preset voltage sudden change threshold is a preset proportion of the rated phase voltage;

[0141] The first judgment result processing unit is used to record the current time as the time when the mutation amount judgment result is yes.

[0142] The second judgment result processing unit is used to determine that no single-phase grounding fault has occurred in the line if the mutation amount judgment result is negative, and then switch back to the step of determining the baseline voltage reference value at the current moment by monitoring the zero-sequence voltage of the bus and performing median filtering in combination with the historical time offset within the sliding time window.

[0143] The transient time length determination unit is used to determine the sampling interval and the transient time length of the coverage fault based on the fault occurrence time and the number of sampling points;

[0144] The fault transient time period determination unit is used to determine the fault transient time period based on the fault occurrence time and the transient time length;

[0145] The sampling unit is used to collect the zero-sequence voltage of the bus and the zero-sequence current of each outgoing line at each moment during the fault transient time period based on the number of sampling points and the sampling interval, so as to determine the zero-sequence voltage data of the bus and the zero-sequence current data of the outgoing lines.

[0146] In some specific embodiments, the transient component extraction module 12 may specifically include:

[0147] The filter acquisition unit is used to acquire a preset Butterworth high-pass filter;

[0148] The component extraction unit is used to perform high-pass filtering on the bus zero-sequence voltage data and the outgoing line zero-sequence current data at each moment in the fault transient time period based on the transfer function corresponding to the preset Butterworth high-pass filter, so as to determine the transient component extraction result.

[0149] In some specific embodiments, the virtual compensation current determination module 13 may specifically include:

[0150] Ground capacitance acquisition unit, used to acquire the ground capacitance of each outgoing line;

[0151] The model acquisition unit is used to acquire a preset virtual compensation current model; wherein, the preset virtual compensation current model is a model constructed based on the principle of electromagnetic induction, the principle of capacitor charging and discharging, the rate of change of the transient component of the zero-sequence voltage of the bus, and a preset capacitive reactance compensation coefficient; the preset capacitive reactance compensation coefficient is a capacitive reactance compensation coefficient determined based on the ground capacitance of the power system.

[0152] The current acquisition unit is used to input the ground capacitance and the bus zero-sequence voltage transient component in the transient component extraction result into the preset virtual compensation current model to determine the virtual compensation current data corresponding to each outgoing line.

[0153] In some specific embodiments, the ground capacitance acquisition unit may specifically include:

[0154] The current injection subunit is used to collect the voltage at the harmonic current injection point and the current of each outgoing line by injecting a harmonic current of a preset frequency into the secondary side of the bus voltage transformer.

[0155] The harmonic extraction subunit is used to extract harmonics from the voltage at the harmonic current injection point and the current of each of the outgoing lines based on a bandpass filter, so as to determine the voltage harmonic components and the current harmonic components corresponding to each of the outgoing lines respectively.

[0156] The capacitance determination subunit is used to determine the capacitance to ground of each of the outgoing lines based on the voltage harmonic components and the current harmonic components corresponding to each of the outgoing lines.

[0157] In some specific embodiments, the transient energy ratio determination module 14 may specifically include:

[0158] An energy determination unit is used to determine the original transient current energy of each of the outgoing lines based on the transient component of the zero-sequence current transient component in the transient component extraction result.

[0159] The compensated energy determination unit is used to determine the compensated transient current energy of each of the outgoing lines by subtracting the transient component of the zero-sequence current of the outgoing line from the corresponding virtual compensated current data.

[0160] An energy ratio determination unit is used to determine the compensated transient energy ratio of each of the outgoing lines based on the original transient current energy and the compensated transient current energy.

[0161] In some specific embodiments, the fault selection module 15 may specifically include:

[0162] The difference determination unit is used to compare the compensated transient energy ratio of the current outgoing line with the average of the compensated transient energy ratios of the other outgoing lines, excluding the current outgoing line, for any of the outgoing lines, so as to determine the transient characteristic difference of the current outgoing line.

[0163] A size sorting unit is used to sort the transient features based on their differences to determine the sorting result.

[0164] The fault selection unit is used to select single-phase grounding faults based on the sorting results in order to determine the selected target fault line.

[0165] Furthermore, embodiments of this application also disclose an electronic device, Figure 4 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content of the diagram should not be construed as limiting the scope of this application.

[0166] Figure 4 This is a schematic diagram of the structure of an electronic device 20 provided in an embodiment of this application. Specifically, the electronic device 20 may include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 stores a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the single-phase ground fault location method disclosed in any of the foregoing embodiments. Alternatively, the electronic device 20 in this embodiment may specifically be a computer.

[0167] In this embodiment, the power supply 23 is used to provide operating voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and external devices, and the communication protocol it follows can be any communication protocol applicable to the technical solution of this application, and is not specifically limited here; the input / output interface 25 is used to acquire external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs, and is not specifically limited here.

[0168] In addition, the memory 22, as a carrier for resource storage, can be a read-only memory, random access memory, disk or optical disk, etc. The resources stored thereon can include operating system 221, computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0169] The operating system 221 is used to manage and control the various hardware devices on the electronic device 20 and the computer program 222, which may be Windows Server, Netware, Unix, Linux, etc. In addition to including a computer program capable of performing the single-phase ground fault location method executed by the electronic device 20 as disclosed in any of the foregoing embodiments, the computer program 222 may further include computer programs capable of performing other specific tasks.

[0170] Furthermore, this application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, it implements the aforementioned single-phase ground fault location method. Specific steps of this method can be found in the corresponding content disclosed in the foregoing embodiments, and will not be repeated here.

[0171] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0172] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0173] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0174] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0175] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A single-phase ground fault line selection method, characterized by, The application is applied to a power system, comprising: determining a bus zero sequence voltage abruptness variable at the current moment based on a baseline voltage reference value at the current moment, and performing single-phase ground fault detection according to the bus zero sequence voltage abruptness variable to obtain a fault detection result; the fault detection result includes a fault occurrence moment and a fault transient time period corresponding to the fault occurrence moment; extracting transient components from bus zero sequence voltage data and outgoing line zero sequence current data corresponding to the fault transient time period in the fault detection result based on a preset high-pass filter to determine a transient component extraction result; determining virtual compensation current data corresponding to each outgoing line based on a preset virtual compensation current model, ground capacitances of each outgoing line, and bus zero sequence voltage transient components in the transient component extraction result; the preset virtual compensation current model includes a preset capacitive reactance compensation coefficient; determining compensated transient energy ratios of each outgoing line based on the virtual compensation current data and outgoing line zero sequence current transient components in the transient component extraction result; determining transient characteristic difference degrees of each outgoing line based on the compensated transient energy ratios of each outgoing line, and performing single-phase ground fault line selection by comparing the sizes of the transient characteristic difference degrees to determine a target fault outgoing line selected.

2. The single-phase earth fault line selection method according to claim 1, characterized in that, The method comprises: determining a baseline voltage reference value at the current moment by monitoring bus zero sequence voltage and combining historical moment offsets in a sliding time window to perform median filtering; determining a bus zero sequence voltage abruptness variable at the current moment based on the baseline voltage reference value at the current moment; determining a fault occurrence moment by determining whether the bus zero sequence voltage abruptness variable is greater than a preset voltage abruptness threshold value; and determining a fault transient time period corresponding to the fault occurrence moment based on the fault occurrence moment and a transient time length covering the fault; collecting bus zero sequence voltage and outgoing line zero sequence current at each moment in the fault transient time period based on the sampling point number and the sampling interval to determine bus zero sequence voltage data and outgoing line zero sequence current data. The method comprises: obtaining a preset Butterworth high-pass filter; ​ 3. The single-phase earth fault line selection method according to claim 2, characterized in that, ​ ​ Based on the transfer function corresponding to the preset Butterworth high-pass filter, the bus zero sequence voltage data and the outgoing line zero sequence current data at each time in the fault transient period are high-pass filtered respectively to determine a transient component extraction result.

4. The single-phase earth fault line selection method according to claim 1, characterized in that, The determination of the virtual compensation current data corresponding to each outgoing line based on the preset virtual compensation current model and the bus zero sequence voltage transient component in the transient component extraction result comprises: Obtaining the ground capacitance of each outgoing line; Obtaining a preset virtual compensation current model; wherein the preset virtual compensation current model is a model constructed based on the principle of electromagnetic induction, the principle of capacitor charging and discharging, the change rate of the bus zero sequence voltage transient component, and a preset capacitive reactance compensation coefficient; the preset capacitive reactance compensation coefficient is a capacitive reactance compensation coefficient determined based on the ground capacitance of the power system; Inputting the ground capacitance and the bus zero sequence voltage transient component in the transient component extraction result into the preset virtual compensation current model to determine the virtual compensation current data corresponding to each outgoing line.

5. The single-phase earth fault line selection method according to claim 4, characterized in that, The obtaining of the ground capacitance of each outgoing line comprises: By injecting a harmonic current of a preset frequency at the secondary side of the bus voltage transformer, the voltage at the harmonic current injection point and the current of each outgoing line are collected; Based on a band-pass filter, the voltage at the harmonic current injection point and the current of each outgoing line are subjected to harmonic extraction to determine a voltage harmonic component and a current harmonic component corresponding to each outgoing line; Based on the voltage harmonic component and the current harmonic component corresponding to each outgoing line, the ground capacitance of each outgoing line is determined.

6. The single-phase earth fault line selection method according to claim 1, characterized in that, The determination of the compensated transient energy ratio of each outgoing line based on the virtual compensation current data and the outgoing line zero sequence current transient component in the transient component extraction result comprises: Based on the outgoing line zero sequence current transient component in the transient component extraction result, the original transient current energy of each outgoing line is determined; By subtracting the outgoing line zero sequence current transient component from the corresponding virtual compensation current data, the compensated transient current energy of each outgoing line is determined; Based on the original transient current energy and the compensated transient current energy, the compensated transient energy ratio of each outgoing line is determined.

7. The single-phase earth fault line selection method according to any one of claims 1 to 6, characterized in that, The determination of the transient characteristic difference degree of each outgoing line based on the compensated transient energy ratio of each outgoing line, and the single-phase ground fault line selection by comparing the size of the transient characteristic difference degree comprise: For any outgoing line, the compensated transient energy ratio of the current outgoing line is compared with the average of the compensated transient energy ratios of the remaining outgoing lines except the current outgoing line to determine the transient characteristic difference degree of the current outgoing line; Based on the size of the transient characteristic difference degree, the sorting result is determined; Based on the sorting result, the single-phase ground fault line selection is performed to determine the target fault outgoing line screened out.

8. A single phase earth fault line selector device characterized in that, Applied to a power system, comprising: The fault detection module is configured to determine a bus zero sequence voltage mutation variable at the current moment based on a baseline voltage reference value at the current moment, and perform single-phase ground fault detection according to the bus zero sequence voltage mutation variable to obtain a fault detection result; the fault detection result includes a fault occurrence moment and a fault transient time period corresponding to the fault occurrence moment; The transient component extraction module is configured to extract transient components from bus zero sequence voltage data and outgoing line zero sequence current data corresponding to the fault transient time period in the fault detection result based on a preset high-pass filter to determine a transient component extraction result; The virtual compensation current determination module is configured to determine virtual compensation current data corresponding to each outgoing line based on a preset virtual compensation current model, ground capacitances of the outgoing lines, and bus zero sequence voltage transient components in the transient component extraction result; the preset virtual compensation current model includes a preset capacitive reactance compensation coefficient; The transient energy ratio determination module is configured to determine compensated transient energy ratios of the outgoing lines based on the virtual compensation current data and outgoing line zero sequence current transient components in the transient component extraction result; The fault line selection module is configured to determine transient feature difference degrees of the outgoing lines based on the compensated transient energy ratios of the outgoing lines, and perform single-phase ground fault line selection by comparing the transient feature difference degrees to determine a target fault outgoing line selected.

9. An electronic device, comprising: The computer program is saved in the memory and executed by the processor to implement the single-phase ground fault line selection method according to any one of claims 1 to 7. The computer program is saved in the memory and executed by the processor to implement the single-phase ground fault line selection method according to any one of claims 1 to 7. The computer program is saved in the memory and executed by the processor to implement the single-phase ground fault line selection method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, ​

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